SLC23A1 (Sodium-dependent Vitamin C Transporter 1)

Overview

The SLC23A1 gene encodes the sodium-dependent Vitamin C transporter 1 (SVCT1). This protein is primarily responsible for the uptake of Vitamin C from the intestine into the blood as well as for the recovery of Vitamin C in the kidneys before it is excreted in the urine.

📍 Chromosomal Position

5q31.2 (Chromosome 5)

🧬 Gene Category

Vitamins

🔬 Inheritance

Complex

📊 Prevalence

G allele ~5-10%

Function & Significance

SLC23A1 (SVCT1) regulates Vitamin C balance on several levels:

Intestinal Absorption: Enables efficient uptake of Vitamin C from food in the small intestine.
Renal Retention: Ensures that filtered Vitamin C is reclaimed in the kidneys to avoid unnecessary loss.
Tissue Supply: Ensures that the blood can supply sufficient Vitamin C to the tissues.
Stress Response: Supports the supply of antioxidants to the body during periods of increased stress.

🍋 The Sluice for Vitamin C

Without a functioning SLC23A1 transporter, the majority of ingested Vitamin C would simply be excreted unused. The gene acts like an intelligent sluice that keeps valuable Vitamin C in the body and channels it into the blood. People with less efficient transporters often need to consume significantly more Vitamin C to reach the same blood levels.

🧬 Relevant SNPs

The variant rs33972313 (Val143Met) has a measurable effect on Vitamin C concentration:

rs33972313
5:138724125

Allele 1

Allele 2

Significance: rs33972313 (A>G) – Also known as the 143Met variant.

• AA (Wild type): Optimal transport capacity.

• GG / AG: Carriers of the G allele have an approx. 40-50% reduced ability to transport Vitamin C, leading to lower plasma levels.

⚠️ Increased Risk for Instability

Individuals with the G allele often show lower Vitamin C levels, which can have consequences for collagen synthesis (connective tissue), the immune system, and protection against oxidative stress. Adequate intake is particularly important for smokers, as smoking massively increases Vitamin C consumption.

🍓 Strategy for G Carriers

If you are a carrier of the G allele, you should consume Vitamin C distributed throughout the day (several small portions rather than one large one) to optimally use the absorption capacity of your transporter. Fresh berries, peppers, kiwis, and citrus fruits are excellent sources.

📚 Data Sources

OMIM: #603791 – Online Mendelian Inheritance in Man
dbSNP: rs33972313 – SNP Database (NCBI)
American Journal of Clinical Nutrition: SLC23A1 and Vitamin C status
Epidemiology: Genetic variation in Vitamin C transporter genes

Last Update: February 2026

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SLC23A1